407awhps4

i just bought a 2001 s4 it was running fine and then it started missfireing, i checked the maf sensor, and it was fine, and i replaced the spark plugs. (they looked pretty worn) it is running much better now, it idles smooth and runs fine if you dont punch it. but is still stummbling at open throttle,and at high rpm..... what could this be?

quickaudi:STFA

is it throwing a CEL?

407awhps4

yes, and the light flashes when i punch the throttle....

quickaudi:STFA

what cylinders is it misfiring on?

407awhps4

im not sure what one it is miss firing on? i can tell it is miss firing though...

quickaudi:STFA

get a vagcom or code scanner to determine which ones it is misfiring on

407awhps4

i have the vagcom on my laptop, but i cant figure out how to get it to scan? do i have to register it to get past the main screen? it is telling me i have to run a test but it wont let me...

ppinto1

measuring blocks for the engine controller. On my A6 w/2.7t, block 15 is 1-3 (passenger side), and block 16 is 4-6 (driver side). The display in the measuring blocks will show misfire counts for the individual cylinders.

If you find misfire on a particular cylinder, try switching its' coil pack with a cylinder it's not happening on - and see if the misfire follows the coil pack.

If it's happening on all cylinders, it may not be coil packs that are at issue. But, if you have a coil pack issue, you should replace all of them (in my opinion). Coil pack issues are very common on our engines - and running in a condition where you're not completely burning your gas could cause your cats to fail.

quickaudi:STFA

go to ross-tech's website
they give you a ton of info and their FAQ is second to none

407awhps4

thank you for the info, that will help greatly! the problem i am having now is getting Vag com running. it is not finding any device attached...